Dual capacity refrigeration



y 1953 T. L. ETHERINGTON 2,841,965

DUAL CAPACITY REFRIGERATION Filed June 29, 1954 2 Sheets-Sheet 1 [n v en for:

Theodore L. i'herv'ngton,

July

Filed June 29, 1954 TENPERA TUNE (F} 1958 T. L. ETHERINGTON 2,841,965

DUAL CAPACITY REFRIGERATION 2 Sheets-Sheet 2 Fig.8.

50 I l I I I I l l caMPos/r/o/v (Mocfi Panes/v7) PERFL uono PROP/9N5 F8) FREO/V a/ (CH: c/Fj Inventor.- Theodore 1... Ether/77813021, by 74 d 4) His Attorney.

United. rates Patent 184L965 i atented July 8, 1958 fifice DUAL CAPACITY REFRIGERATION Theodore L. Etherington, ldailston Lake, N. Y., assignor to General Electric Company, a corporation of New York Application June 29, W54, Serial No. 440,021

ti Claims. (Cl. 62-513) This invention relates to refrigeration systems and specifically to a method and apparatus to secure dual capacity refrigeration in such systems.

Dual capacity refrigeration systems are desirable in heat pump construction and in commercial and domestic refrigerators. It is desirable that a reverse refrigeration system or heat pump employ a variable refrigerant mixture to match capacity with load over a wide variation in the evaporator temperatures. A single refrigerant system will not match capacity with load over such temperature variations.

Accordingly, it is an object of my invention to provide a new and improved refrigeration system in which a refrigerant mixture of variable composition is employed.

It is another object of the invention to provide a refrigeration system which selectively circulates a refrigerant mixture of variable composition in response to the load upon the system.

It is a further object of the invention to provide a novel method of refrigeration in which a variable composition of refrigerants is circulated in the refrigeration system.

In carrying out my invention in one form, a refrigerant mixture of variable composition is selectively circulated in a refrigeration system to provide variable temperature levels of refrigeration.

These and various other objects, features and advantages of the invention will be better understood from the following description taken in connection with'the accompanying drawings in which:

Fig. l is a schematic view of one form of a refrigeration system which embodies my invention;

Fig. 2 is a schematic view of a second form of a refrigeration system which embodies my invention; and

Fig. 3 is a solubility graph of a perfluoropropane (C 1 and Freon 31 (CH CIF) mixture at system pressure in which composition in mole percentage is plotted against the temperature in degrees Fahrenheit.

In Fig. 1 of the drawings, a dual capacity refrigeration system which may be used in heat pump construction or in commercial or domestic refrigeration devices and which is indicated generally at 10, comprises a com pressor 11 which communicates on its high pressure side with a condenser'12. Condenser 12 is connected to an insulated liquid receiver 13 in which there are shown a pair of low temperature substantially immiscible refrigerants 14 and 15 in two separate liquid layers. A threeway valve 16 controls a pair of outlets 17 and 18 which communicate with the refrigerants 14 and 15, respectively. A load sensing device 19 of any conventional construction may be provided to selectively operate the valve 16 in response to the system load which is sensed by a temperature responsive device 9 connected by means of a lead 8 to control 19. A valve outlet 20 circulates one of the refrigerants from three-way valve 16 through an expansion valve 21 to a heat exchange coil 22 within receiver 13. Coil 22 is connected to an outlet 23 in communication with the inlet side of an evaporator 24. Coil 22 is positioned in insulated receiver 13 to cool the pair of refrigerants 14 and 15 to evaporator temperature. The insulation of receiver 13 retains the refrigerant pair at such temperature. Expansion valve 21 is shown to be a conventional type which is operated by a pressure tube 25 and diagram 26. A temperatureoperated or thermostatic valve or sections of capillary tubing may be employed as the expansion device. Evaporator 24 is connected to the inlet or low pressure side of compressor 11 to complete the refrigeration system. Compressor 11 is controlled by control 19 in being electrically connected thereto by lead 7.

The pair of refrigerants 14 and 15 which have difierent volatility, solubility and density characteristics are circulated separately or as a mixture through the refrigeration system in response to the load thereon. It is important that each of the refrigerants which is selected for circulation in the system has a different density from the other refrigerant and exhibits insolubility in the other refrigerant of the pair at or below the lower customary evaporator temperatures to provide a separation of the refrigerants into two layers in liquid receiver 13. The following pairs of refrigerants, which exhibit different volatility, solubility and density and which possess good immiscibility at the lower customary evaporator temperatures, are given as examples of suitable combinations to be employed in a dual capacity refrigeration system: pertiuoro-propane (C 1 and Freon 21 (CHCI F), perfluoropropane (C 1 and methyl chloride (CH Cl), perfluoropropane (C F and Freon 31 (CI-I CIF), perliuorobutane (C F and Freon 21 (CHCl F), perfluorobntane (C F and methyl chloride (CH Cl), Freon 11'5 (C F Cl) and sulfur dioxide (S0 perfluoropropane (C F and methyl bromide (CH Br), Freon (C F Cl) and methyl chloride (CH CI perfluorobutane (C 11 and methylene chloride (CH Cl perfiuorobutane (C F and ethyl chloride (C H Cl).

In the operation of the refrigeration system in Fig. l,

the pair of refrigerants 14 and 15, which form two layers in liquid receiver 13 at the lower evaporator tempera tures and a soluble solution at the higher evaporator temperatures, are selectively circulated in the system in response to the load thereon. Valve 16 is shown in open position for outlet 18 and in closed position for outlet 17 to provide refrigerant 15 in the system. Compressor 11 pumps refrigerant 15 through condenser 12 to insulated liquid receiver 13 where it separates into its respective leaving the liquid receiver becomes a direct function of the evaporator temperature. The pair of refrigerants are mutually soluble at the higher portion of the operating temperature range for the evaporator but they are substantially mutually immiscible at the lower evaporator temperatures. Above a certain evaporator temperature,

which is determined by the refrigerants and their com- I position, the pair of refrigerants exist as a solution in the liquid receiver. the refrigerants exist in separate immiscible layers. If

the predominately high boiling refrigerant is withdrawn from the receiver, modulation occurs in the direction of Below such evaporator temperature,

decreased capacity at low evaporator temperatures. If the low boiling refrigerant is withdrawn from the receiver, the modulation occurs in the direction of increase-d capacity at low evaporator temperatures. Load sensing device 19 permits withdrawal of either refrigerant 14 or to provide-modulation in the direction of either high or low capacity at low temperatures.

In Fig. 2, a modified form of refrigeration system is shown which comprises a compressor 11 connected on its high pressure side with condenser 12. Condenser 12 communicates with insulated liquid receiver 13 in which there are shown a pair of low temperature substantially immiscible refrigerants 14 and 15 in two separate liquid layers. A receiver outlet 27 connects receiver 13 with evaporator 24 which communicates with the inlet or low pressure side of compressor 11. Outlet 27 is located adjacent to the top of liquid receiver 13 to insure that the refrigerant which is circulated through evaporator 24 is always withdrawn from the surface of the liquid in receiver 13. Expansion valve 21 is positioned between condenser 12 and liquid receiver 13 to cool the refrigerants 14 and 15 to evaporator temperatures.

When the refrigeration system is charged with a pair of refrigerants 14 and 15 which are mutually soluble at the higher portion of evaporator temperatures but mutually substantially immiscible at the lower evaporator temperatures, the composition of the refrigerant which is circulated in the system becomes a direct function of the evaporator temperature. At evaporator temperatures above which the pair of refrigerants Id and 15 form two liquid layers, the refrigerant which leaves the receiver is a solution of composition as charged to the system. At evaporator temperatures below which two liquid layers appear, the refrigerant which flows from the receiver is a solution whose composition is that of the top liquid layer. A capacity change occurs of magnitude proportional to the composition change in the circulating refrigerant. The direction of capacity change is determined by the volatility of that refrigerant which has the lower liquid density. Thus, the capacity is increased with higher volatility and decreased with lower volatility.

The refrigeration system, which is shown in Fig. 2, is similar in construction and operation to the system disclosed in Fig. 1. Accordingly a detailed description of the operation of this modified system is not believed necessary.

In Fig. 3, there is shown a solubility graph of a perfluoropropane (C F and Freon 31 (CH ClF) mixture in which composition in mole percentage is plotted against the temperature in degrees Fahrenheit. Such a refrigerant mixture is generally miscible above 44 F. and substantially immiscible below this temperature. If the temperature of the refrigerants 14 and 15 in the receiver I3 is assumed to be F. for purposes of illustration, one immiscible refrigerant layer is composed of 85.5% by weight of perfluoropropane and 14.5% by weight of Freon 31. The other refrigerant layer is 84% Freon 31 and 16% perfluoropropane.

As will be apparent to those skilled in the art, the objects of my invention are attained by the use of a refrigerant mixture of variable composition which is selectively circulated in a refrigeration system to provide variable temperature levels of refrigeration.

While other modifications of this invention and variations of apparatus which may be employed within the scope of the invention have not been described, the invention is intended to include all such as may be embraced within the following claims.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a refrigeration system including a receiver and an evaporator, a compressor and a condenser, a pair of refrigerants in said receiver, said refrigerants being at a first temperature range substantially immiscible and at a second temperature range substantially, mutually soluble, means for circulating a solution of said refrigerants through said system at said second temperature range, means for cooling the refrigerants in the receiver to vary the solubility thereof as a function of evaporator temperature, and means to selectively circulate one of said refrigerants when said first range of temperature is attained.

2. In a refrigeration system including a receiver, and an evaporator, a compressor and a condenser, a pair of refrigerants in said receiver, said refrigerants being at a first temperature range substantially immiscible and at a second temperature range substantially, mutually soluble, means for circulating a solution of said refrigerants through said system at said second temperature range, means for utilizing the cooling properties of the circulating refrigerant to vary the solubility of the refrigerants within the said receiver as a function of evaporating temperature, and means to selectively circulate one of said refrigerants at said first temperature range.

3. In a refrigeration system including a receiver, an evaporator, a compressor and a condenser, a pair of refrigerants in said receiver, said refrigerants being at a first temperature range substantially immiscible and at a second temperature range substantially, mutually soluble, means for circulating a solution of said refrigerants through said system to attain said second temperature range, means for passing the circulating refrigerant in heat exchange relationship with the refrigerant in said receiver to vary the solubility thereof as a function of the evaporator temperature, and means for selectively circulating one of said refrigerants through said system in said first temperature range.

4. In a refrigeration system including a receiver, an evaporator, a compressor and a condenser, the combination comprising a pair of refrigerants in said receiver, said refrigerants being substantially immiscible at a first temperature range and substantially, mutually soluble at a second temperature range, a heat exchanger coil in said receiver, said heat exchanger coil connected to said evaporator, and means for circulating a solution of said refrigerants through said system during said second temperature range operation, said circulating refrigerant passing through said heat exchanger coil whereby the immiscibility stage of the refrigerants in the receiver becomes a function of the evaporator temperature, and means for selectively circulating one of said refrigerants through said system during operation in said first temperature range.

5. In a refrigeration system including a receiver, and an evaporator, a compressor and a condenser, a pair of refrigerants in said receiver, said refrigerants being at a first temperature range substantially immiscible and at a second temperature range substantially, mutually soluble, means for circulating a solution of said refrigerants through said system, and means including cooling the circulating refrigerant solution from the condenser before entry into the receiver whereby the temperature of the refrigerant in said receiver becomes a function of evaporator temperature, and the composition of the circulating refrigerant is varied.

6. In a refrigeration system including a receiver, and an evaporator, a compressor and a condenser, a pair of refrigerants in said receiver, said refrigerants being at a first temperature range substantially immiscible and at a second temperature range substantially, mutually soluble, means for circulating a solution of said refrig erants through said system during said second temperature range, and expansion valve means between said condenser and said receiver whereby the circulating refrigerant solution entering the said receiver is pre-cooled to maintain the temperature of the refrigerant in said receiver as a function of evaporator temperature, and vary the composition of the circulating refrigerant.

7. in a refrigeration system including a receiver, and an evaporator, a compressor and a condenser, a pair of refrigerants in said receiver, said refrigerants being at a first temperature range substantially immiscible and at a second temperature range substantially, mutually soluole, means for circulating a solution of said refrigerants through said system, coolant means for cooling the circulating refrigerant from the condenser prior to entry into the receiver to vary the composition of the refrigerants therein, said circulating means including a sole outlet from the top level of the refrigerant in said receiver, whereby under a predetermined condition only one refrigerant is circulated, and under another predetermined condition a mixture of refrigerant is caused to circulate.

8. The structure as claimed in claim 7 wherein said coolant means comprises an expansion valve between the said condenser and the said receiver.

Newton Mar. 24, 1942 Hintze July 2, 1946 

